Port velocities

[106-1194218389]

I have added a drawing that shows the major airflow path shown by the string at three different parts of the port. The red, blue and green lines represent the string when held at different parts of the port at the opening at the intake manifold side.

[larrycavan]

[106-1194218389]

Yes Larry, I really need to add some real suck to this bench. Here though are my latest results. I have been fighting some real turbulance at .550" which is just about convergence. Just about anything I did to the port was not really showing any real results at the .550" lift where all the reat of the lifts were looking pretty good. I have been running a Milodon Megaflow 2.05" intake which has a pretty thin flat back side. I put in a Del West titanium valve which is fatter on the backside of the valve and is back cut 30 degrees. I have included a picture of those here. The Milodon is on the left and the Del West is on the right: Results below
Velocities first then CFM flow with stability readings
Mildodon Del West
pushrod SSR Pushrod SSR
350 326 303 267 247 247 350 319 303 226 226 251
356 319 296 286 286 293 350 319 303 286 303 286
319 306 286 350 378 350 319 303 267 364 364 364

Milodon Del West
lift CFM Stability lift CFM Stability
.050" 29.5 .34 .050" 31.3 .50
.100" 60.7 .47 .100" 63.0 .58
.150" 94.6 .53 .150" 97.1 .61
.200" 125.6 .95 .200" 128.7 .55
.250" 155.0 .51 .250" 158.0 .43
.300" 180.1 .65 .300" 183.0 .85
.350" 204.1 .82 .350" 202.6 .73
.400" 222.0 .95 .400" 221.1 .76
.450" 243.3 .91 .450" 237.3 .77
.500" 256.9 .85 .500" 245.1 .68
.550" 251.0 5.48 .550" 249.7 .64
.600" 244.4 1.09 .600" 251.9 1.15
.650" 249.5 1.12 .650" 252.7 1.23
.700" 253.3 1.40 .700" 252.4 .97
.750" 255.0 1.04 .750" 252.2 1.34
.800" 255.6 2.01 .800" 253.0 1.58
on stability the lower the number the better
photo of valves Milodon on left and Del West on right

[106-1194218389]

Try the picture again. Once in awhile when I up load they hose up for some reason

[larrycavan]

Interesting Test John....

I imported the last group of data into Excel and looked things over...Here's the results

Averaging out the Stability through .800" lift, the Del West is the clear winner.

1.2 - .84 [Del West]

Same thing but only through .450" lift [your cam choice]

.68 - .64 [Del West]

Average Flow through .800 lift

192.5 - 192.4 [no real winner

Average Flow through .450 lift

146.1 - 146.9 [ Del West by a hair]

[stevenford]

[106-1194218389]

[color=#000000]Thanks Larry,
I have another set of 2.050" valves that I have flowed and they are a little better than the Milodon but not as good as the Del West. The shape is between the Del West and the Milodon. Tomorrow I am going to go face the Milodon and the other one to have a thinner margin and then back cut both of those. I will probably back cut with 35

[larrycavan]

Maybe try a narrower back cut and then sneak up on it.

Tests like that are really interesting. Isn't it amazing how things can flip flop back and forth....

[stevenford]

[bruce]

Here is a little tip I do when testing valve designs. I machined a valve stem from alum and threaded the end. I then install a piece of solid round pvc in place of a valve head. I can then chuck this up in my lathe and turn a head design for testing. Very cost effective for testing "what-if's", once I have a design that works I then can machine/grind the same design on a valve blank.

[larrycavan]

Look at .450 - .550.....then wham! at .600 another dramatic swap. What are you using for a port entrance radius guide?

I also wonder what happens if you machine the stem on the DW down like the other valve....



Edited By larrycavan on 1207523515

[106-1194218389]

This is what I am using for an intake flow adaptor for the port entrance - this picture is before I did any porting so I do not have that big edge there. It matches the port perfectly now.

[larrycavan]

Nice John!

I was hoping you had something that was 100% repeatable....that certainly is!

[106-1194218389]

It is made from 3/4" pvc. I really like PVC to work with and it looks like Bruce likes it also. Hey, Bruce great idea on the valve! I never thought about that but what a neat thing to do. PVC is so easy to work with. I just happen to have some PVC here I can use.

John

[106-1194218389]

[color=#000000]Well I went to a friends head shop and we back cut two of my valves. The Milodon, which did not work as well as the others un-back cut, we faced until the margin is just .025"(made my friend shudder) and then back cut 35